Two vulnerable Democrats voted against the bill: Ann Kirkpatrick of Arizona and John F. Tierney of Massachusetts.

Overall, 39 Democrats joined with the vast majority of Republicans in order to pass the bill; 23 of those 39 Democrats are rated as vulnerable to some degree. Unlike their fellow delegate Kirkpatrick, Arizona Reps. Ron Barber and Kyrsten Sinema voted for the bill.

What’s also striking about Kirkpatrick and Tierney is how different their districts and political situations are.

In contrast, Barack Obama and John Kerry carried Massachusetts’s 6th District with at least 55 percent in the last three presidential contests. But Tierney faces an increasingly serious challenge in the primary, and the congressman could be concerned that supporting any effort to delay or derail the president’s signature piece of legislation could hurt him with a Democratic electorate.

Tierney is also likely to face a competitive rematch against Republican Richard Tisei in the general election. The congressman was re-elected to a ninth term in 2012 by defeating Tisei by 1 point. Massachusetts’s 6th District is currently rated Leans Democrat by Rothenberg Political Report/Roll Call.